(1) Field of the Invention
The present invention relates to a food material for puffing, which can be easily puffed by heating, in particular by heating in a microwave oven, so that there can be obtained a puffed food such as a rice cracker.
(2) Description of the Prior Art
Puffed foods such as puffed rice crackers or puffed cereal grains are widely marketed. As a rule, it is necessary to use a special pressure-type appliance for puffing food, and, therefore, it is difficult to puff food at home. However, since selling food in a pre-puffed condition lowers the cost of transportation and puffing the food just before eating gives it better taste, smell and texture, much research has been conducted toward realizing a food material which enables easy puffing at home. For example, Japanese Patent Pre-examined Publication (KOKAI) No. 12264/1975 discloses a process for preparing a food material cooked by a microwave oven, which comprises kneading and rolling pre-gelatinized cereal grain; dehydrating the grain to a water content of between 13 and 28 weight %; and mixing the resulting solid material with 5 to 30% by weight of fat or oil. In this connection, the publication also discloses that the food material thus obtained easily produces a baked cracker by heating in a microwave oven. However, the food material thus obtained has faults in that the crackers formed of the food material adhere to each other when they are heated in a microwave oven, and the degree of puffing is not uniform.
Japanese Patent Pre-examined Publication (KOKAI) No. 136859/1976 further discloses a process for preparing food material for puffing, which comprises drying a rice cake (Japanese MOCHI) until the water content thereof is between 20 and 30 weight %; and adding water thereto before heating it in a microwave so as to increase the surface water content of the dried rice cake 5 to 15 weight % higher than the inner water content thereof. However, this method can neither prevent adherence of the rice cakes to each other nor accomplish uniform and high puffing of the cakes.